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James Hensman

25 accepted papers

2024

Learning to Extract Structured Entities Using Language Models

EMNLP 2024main

Recent advances in machine learning have significantly impacted the field of information extraction, with Language Models (LMs) playing a pivotal role in extracting structured information from unstructured text. Prior works typically represent information extraction as triplet-centric and use classi…

2024

QuaRot: Outlier-Free 4-Bit Inference in Rotated LLMs

NeurIPS 2024poster

We introduce QuaRot, a new Quantization scheme based on Rotations, which is able to quantize LLMs end-to-end, including all weights, activations, and KV cache in 4 bits. QuaRot rotates LLMs in a way that removes outliers from the hidden state without changing the output, making quantization easier.…

2024

SliceGPT: Compress Large Language Models by Deleting Rows and Columns

ICLR 2024poster

Large language models have become the cornerstone of natural language processing, but their use comes with substantial costs in terms of compute and memory resources. Sparsification provides a solution to alleviate these resource constraints, and recent works have shown that trained models can be sp…

2021

Deep Neural Networks as Point Estimates for Deep Gaussian Processes

NeurIPS 2021poster

Neural networks and Gaussian processes are complementary in their strengths and weaknesses. Having a better understanding of their relationship comes with the promise to make each method benefit from the strengths of the other. In this work, we establish an equivalence between the forward passes of…

Cited by 46SourcePDFScholar
2020

Amortized variance reduction for doubly stochastic objective

UAI 2020poster

Approximate inference in complex probabilistic models such as deep Gaussian processes requires the optimisation of doubly stochastic objective functions. These objectives incorporate randomness both from mini-batch subsampling of the data and from Monte Carlo estimation of expectations. If the gradi…

Cited by 5SourcePDFScholar
2020

Bayesian Image Classification with Deep Convolutional Gaussian Processes

AISTATS 2020poster

In decision-making systems, it is important to have classifiers that have calibrated uncertainties, with an optimisation objective that can be used for automated model selection and training. Gaussian processes (GPs) provide uncertainty estimates and a marginal likelihood objective, but their weak i…

Cited by 47SourcePDFScholar
2020

Doubly Sparse Variational Gaussian Processes

AISTATS 2020poster

The use of Gaussian process models is typically limited to datasets with a few tens of thousands of observations due to their complexity and memory footprint.The two most commonly used methods to overcome this limitation are 1) the variational sparse approximation which relies on inducing points and…

2020

Sparse Gaussian Processes with Spherical Harmonic Features

ICML 2020poster

We introduce a new class of inter-domain variational Gaussian processes (GP) where data is mapped onto the unit hypersphere in order to use spherical harmonic representations. Our inference scheme is comparable to variational Fourier features, but it does not suffer from the curse of dimensionality,…

2019

Banded Matrix Operators for Gaussian Markov Models in the Automatic Differentiation Era

AISTATS 2019poster

Banded matrices can be used as precision matrices in several models including linear state-space models, some Gaussian processes, and Gaussian Markov random fields. The aim of the paper is to make modern inference methods (such as variational inference or gradient-based sampling) available for Gauss…

Cited by 40SourcePDFScholar
2019

Deep Gaussian Processes with Importance-Weighted Variational Inference

ICML 2019oral

Deep Gaussian processes (DGPs) can model complex marginal densities as well as complex mappings. Non-Gaussian marginals are essential for modelling real-world data, and can be generated from the DGP by incorporating uncorrelated variables to the model. Previous work in the DGP model has introduced n…

2019

Overcoming Mean-Field Approximations in Recurrent Gaussian Process Models

ICML 2019oral

We identify a new variational inference scheme for dynamical systems whose transition function is modelled by a Gaussian process. Inference in this setting has either employed computationally intensive MCMC methods, or relied on factorisations of the variational posterior. As we demonstrate in our e…

2019

Pseudo-Extended Markov chain Monte Carlo

NeurIPS 2019poster

Sampling from posterior distributions using Markov chain Monte Carlo (MCMC) methods can require an exhaustive number of iterations, particularly when the posterior is multi-modal as the MCMC sampler can become trapped in a local mode for a large number of iterations. In this paper, we introduce the…

2018

Gaussian Process Conditional Density Estimation

NeurIPS 2018poster

Conditional Density Estimation (CDE) models deal with estimating conditional distributions. The conditions imposed on the distribution are the inputs of the model. CDE is a challenging task as there is a fundamental trade-off between model complexity, representational capacity and overfitting. In th…

2018

Learning Invariances using the Marginal Likelihood

NeurIPS 2018poster

In many supervised learning tasks, learning what changes do not affect the predic-tion target is as crucial to generalisation as learning what does. Data augmentationis a common way to enforce a model to exhibit an invariance: training data is modi-fied according to an invariance designed by a human…

2018

Natural Gradients in Practice: Non-Conjugate Variational Inference in Gaussian Process Models

AISTATS 2018poster

The natural gradient method has been used effectively in conjugate Gaussian process models, but the non-conjugate case has been largely unexplored. We examine how natural gradients can be used in non-conjugate stochastic settings, together with hyperparameter learning. We conclude that the natural g…

Cited by 0SourcePDFScholar
2017

Identification of Gaussian Process State Space Models

NeurIPS 2017poster

The Gaussian process state space model (GPSSM) is a non-linear dynamical system, where unknown transition and/or measurement mappings are described by GPs. Most research in GPSSMs has focussed on the state estimation problem, i.e., computing a posterior of the latent state given the model. However,…

Cited by 148SourcePDFScholar
2016

On Sparse Variational Methods and the Kullback-Leibler Divergence between Stochastic Processes

AISTATS 2016poster

The variational framework for learning inducing variables (Titsias, 2009) has had a large impact on the Gaussian process literature. The framework may be interpreted as minimizing a rigorously defined Kullback-Leibler divergence between the approximating and posterior processes. To our knowledge thi…

Cited by 173SourcePDFScholar
2015

MCMC for Variationally Sparse Gaussian Processes

NeurIPS 2015poster

Gaussian process (GP) models form a core part of probabilistic machine learning. Considerable research effort has been made into attacking three issues with GP models: how to compute efficiently when the number of data is large; how to approximate the posterior when the likelihood is not Gaussian an…

Cited by 178SourcePDFScholar
2015

Scalable Variational Gaussian Process Classification

AISTATS 2015poster

Gaussian process classification is a popular method with a number of appealing properties. We show how to scale the model within a variational inducing point framework, out-performing the state of the art on benchmark datasets. Importantly, the variational formulation an be exploited to allow classi…